This invention relates to a mounting aid for a sub-assembly of actuating elements for tappet valves of internal combustion engines. The sub-assembly has at least one coil spring adapted to coaxially surround the valve stem and extending axially from a valve spring support disc (hereafter "spring retainer") and may be bounded at its other end by a spring seat ring. Segmented locking wedges (hereafter "split collar") are accommodated in a central conical opening of the spring retainer and are held in place by a closing disc which partially blocks the conical opening. The closing disc, which constitutes the mounting aid, prevents the split collar from falling out of the conical opening.
The above-outlined arrangement is disclosed, for example, in U.S. Pat. No. 2,855,915. During the mounting of the sub-assembly in the internal combustion engine, the split collar is shifted by the valve stem axially in the direction of the closing disc, whereby the inner diameter of the split collar is increased to such an extent that the valve stem can be axially pushed therethrough. At the same time, the elastomer closing disc exerts an axial return force on the split collar so that upon reaching the corresponding circumferential groove in the valve stem, the split collar is returned into its original radial position and thus the spring retainer is axially immobilized relative to the valve stem.
The closing disc is designed to remain connected with the spring retainer after the mounting operation and can then function as a sealing body which seals the valve stem from lubricant oil. This circumstance, however, leads in present-day engines to an insufficient lubrication of the valve stem seals, as a result of which the sealing lips of the valve stem seals are exposed to increased wear. It is a further disadvantage of known mounting aids of this type that for securing the spring retainer only a split collar having a radially oriented projection formed as a circumferential web can be used for cooperating with a corresponding groove provided circumferentially in the valve stem, for the purpose of an axial immobilization of the wedges on the valve stem.